i

The EPA/OSHA Joint Accident Investigation Program

EPA and OSHA work together under conditions detailed in a Memorandum of

Understanding (MOU) to investigate certain chemical accidents. The fundamental objective of

the Joint EPA/OSHA chemical accident investigation program is to determine and report to the

public the facts, conditions, circumstances, and causes or likely causes of any chemical accident

that results in a fatality, serious injury, substantial property damage, or serious off-site impact,

including a large scale evacuation of the general public. The ultimate goal of the accident

investigation is to determine the root causes in order to reduce the likelihood of recurrence,

minimize the consequences associated with accidental releases, and to make chemical production,

processing, handling, and storage safer. This report is a result of a Joint EPA/OSHA investigation

to describe the accident, determine root causes and contributing factors, and identify findings and

recommendations.

Under section 112(r)(1) of the Clean Air Act Amendments of 1990 (CAA) and under the

OSH Act of 1970, industry has a general duty to design and maintain a safe facility taking such

steps as are necessary to prevent releases, and to minimize the consequences of accidental releases

which do occur, and to provide a safe and healthy workplace for workers. In addition, OSHA

has promulgated the Process Safety Management Standard at 29 CFR 1910.119 for the

prevention of chemical accidents that impact workers. EPA, under section 112(r)(7) of the CAA,

has promulgated regulations for the preparation of risk management programs and plans for the

prevention of accidental chemical releases that harm the public and the environment. However,

compliance and enforcement with these provisions are not the focus of this report but will be

addressed by EPA, OSHA or both as necessary in separate reports or actions.

Prior to releasing an accident investigation report, OSHA and EPA must ensure that the

report contains no confidential business information. The Freedom of Information Act (FOIA),

the Trade Secrets Act, and Executive Order 12600 require federal agencies to protect confidential

business information from public disclosure. To meet these provisions, OSHA and EPA have

established a clearance process for accident investigation reports in which the companies who

have submitted potentially confidential information used in the report are provided a portion of

the draft report. This portion contains only the factual details related to the investigation (not the

findings, the conclusions nor the recommendations). Companies are asked to review this factual

portion to confirm that the draft report contains no confidential business information. As part of

this clearance process, companies often will provide to OSHA and EPA additional factual

information. In preparing the final report, OSHA and EPA consider and evaluate any such

additional factual information for possible inclusion in the final report.

Chemical accidents investigated by EPA Headquarters are conducted by the Chemical

Accident Investigation Team (CAIT) located in the Chemical Emergency Preparedness and

Prevention Office (CEPPO) at 401 M Street SW, Washington, DC 20460, 202-260-8600. More

information about CEPPO and the CAIT may be found at the CEPPO Homepage on the Internet

at http://www.epa.gov/ceppo. Copies of this report can be obtained from the CEPPO Homepage
ii

or by calling the National Service Center for Environmental Publications (NSCEP) at 800-

490-9198. OSHA Headquarters are located in the US Department of Labor - OSHA, 200

Constitution Ave NW, Washington, DC, 20210, 202-219-8118. More information about OSHA

may be found at the OSHA Homepage on the Internet at http://www.osha.gov.

Chemical Safety and Hazard Investigation Board (CSB)

In the 1990 Clean Air Act Amendments, Congress created the Chemical Safety and

Hazard Investigation Board (CSB). Modeled after the National Transportation Safety Board

(NTSB), the CSB was directed by Congress to conduct investigations and report to the public the

findings regarding the causes of chemical accidents. Congress authorized funding in November

1997 and the CSB began operations in January 1998. Several investigations by the CSB are

underway. More information about CSB may be found at their Homepage on the Internet at

http://www.chemsafety.gov or http://www.csb.gov.

EPA and OSHA plan to complete their work and issue public reports on investigations

initiated prior to funding of the CSB. Under their existing authorities, both EPA and OSHA will

continue to have roles and responsibilities in responding to, and investigating, chemical accidents.

 The CSB, EPA, and OSHA (as well as other agencies) will be coordinating their efforts to

determine the causes of accidents and to apply lessons learned to prevent future events.
iii

Executive Summary

On May 8, 1997, at approximately 1:15 p.m., Central Daylight Time , a massive explosion

and fire occurred at Unit Two of the Bartlo Packaging Incorporated (BPS) facility located in

West Helena, Arkansas. As a result of the explosion and fire, three West Helena firefighters were

killed. Seventeen firefighters required medical attention due to heat exhaustion and injuries

during the response. The Unit Two structure was completely destroyed. Hundreds of residents

and patients at a local hospital were either evacuated or sheltered-in-place. The Mississippi river

traffic and major roads were closed for approximately twelve hours due to the release of toxic

materials from the facility.

Prior to the explosion, BPS employees observed smoke in the Unit Two warehouse.

Following established procedures, all employees evacuated the building. The company placed an

emergency call to local emergency response groups. Members of the West Helena Fire

Department (WHFD) responded to the scene within minutes. A reconnaissance team composed

of four firefighters was outside of the Unit Two warehouse when an explosion occurred inside the

building. Three firefighters were fatally injured when they were struck by materials blown out of

a falling cinder block wall. The fourth firefighter was seriously injured.

EPA and the OSHA conducted a joint investigation of the incident. The Joint Chemical

Accident Investigation Team (JCAIT) determined that the incident was most likely caused by the

decomposition of a bulk sack containing the pesticide Azinphos methyl (AZM) 50W which had

been placed against or close to a hot compressor discharge pipe. Under this scenario, the heat

from the discharge pipe would have caused the pesticide material to decompose and give off

flammable vapors which resulted in the fatal explosion.

 The investigation team could not eliminate the possibility that the AZM 50W arriving at

BPS the day of the accident was already decomposing. This alternate scenario could either be an

initiating event by itself or a factor influencing the preferred scenario. In other words, a

decomposing bag of AZM 50W could have been placed closed to the compressor discharge pipe.

The JCAIT identified the following root causes and contributing factors of the event:

$ MicroFlow Company (MFC) and BPS did not have a full understanding of the hazards

associated with AZM.

$ BPS did not assess the potential hazards of a hot pipe in an area where hazardous

chemicals were to be stored when the new warehouse addition was constructed.

$ BPS did not have standard operating procedures for material storage and handling.

$ On-site information provided to the WHFD was conflicting and incomplete.
iv

The following recommendations were developed by the JCAIT to address the root causes

and contributing factors and to prevent recurrence of similar incidents at other facilities:

$ Manufacturers should be proactive in testing potentially hazardous materials. Testing for

actual conditions and elevated temperatures during storage should be conducted to

determine safe storage conditions. Screening tests, such as Differential Scanning

Calorimetry (DSC), can be helpful in determining the need for additional testing. 

However, thermally unstable materials which are intended to be packed and shipped in

large volume containers should be tested beyond screening levels.

$ Facilities which store, use, handle, manufacture or move hazardous materials should

develop and implement a system to review potential hazards of modifications to facilities,

equipment, chemicals, technology, or procedures. The system should analyze potential

impacts to safety, health, and the environment and take appropriate actions before the

modifications are implemented. OSHA=s Process Safety Management (PSM), EPA=s Risk

Management Program (RMP), and the Center for Chemical Process Safety (CCPS)

guidelines can help facilities develop such system.

$ Facilities that store hazardous chemicals should develop standard operating procedures for

material storage and handling that address storage restrictions. Such facilities should

adhere to applicable practices outlined by CCPS and the National Fire Protection

Association (NFPA). Pesticide facilities are encouraged to also follow NFPA 43D (Code

for the Storage of Pesticides), specifically the non-mandatory Appendix B.

$ Facilities storing hazardous chemicals should develop an inventory management system

with information regarding composition, compatibility, storage, location, and quantity of

incoming products. This management system can help the facility comply with storage

restrictions and provide emergency responders useful information during a response

action.

$ EPA and OSHA, in conjunction with interested parties, should facilitate a workshop to

make recommendations on how to improve the quality of hazardous materials information

available during response actions. The workshop should review appropriate uses of

Material Safety Data Sheets by local emergency response groups and how to provide

these groups information describing the behavior of hazardous materials when they begin

to react or decompose and what responders should look for during a chemical emergency.
v

Table of Contents

Page

1.0 Background.....................................................................................................................1

1.1 Introduction .........................................................................................................1

1.2 Facility Description ..............................................................................................1

1.3 Chemicals in the New Warehouse Addition ..........................................................4

2.0 Description of the Incident...............................................................................................5

2.1 Sequence of Events..............................................................................................5

2.2 Emergency Response Actions............................................................................. 10

BPS Emergency Preplanning .............................................................................. 10

Initial Response.................................................................................................. 10

Response Actions Under the Incident Command System .................................... 11

2.3 Public Health and Environmental Issues.............................................................. 12

3.0 Investigation and Analysis.............................................................................................. 13

3.1 Investigation ...................................................................................................... 13

3.2 Analysis ............................................................................................................. 14

3. 2. A Overview of Explosion Scenarios.......................................................... 14

Scenario 1: Chemical in Supersack Decomposes when Placed Close to

the Compressor Header Pipe............................................ 15

Scenario 2. AZM decomposition begins before arriving to BPS.......... 23

Scenario 3. Incompatible Chemicals React ......................................... 25

Scenario 4. Malfunctioning Compressor Overheats Supersacks Near the

After-cooler Piping.......................................................... 28
vi

3. 2. B Overview of Early Emergency Response................................................. 28

On-site information................................................................................. 29

Risk Perception/Risk Management.......................................................... 31

4.0 Root Causes and Recommendations............................................................................... 32

4.1 Root Causes and Contributing Factors ............................................................... 32

4.2 Recommendations.............................................................................................. 33
vii

List of Figures

 Page

1. Floor Plan-BPS, Inc. Unit Two....................................................................................2

2. New Warehouse Addition Compressor System............................................................3

3. After-cooler................................................................................................................4

4. Compressor Discharge Pipe After the Incident..... ......................................................4

5. Supersack set-up at BPS Unit One............................................................................17

6. Aerial Photo BPS Unit Two......................................................................................18

7. Approximate Location of Chemicals in the New Warehouse Addition.......................19

8. Ventilation Fan with Yellow Residue........................................................................20

Appendices

Page

$ Material Safety Data Sheets for Maneb 75DF, Azinphos methyl 50W, and Alliette

Signature WDG ......................................................................................................35

$ Summary of Laboratory Results..............................................................................52

$ References..............................................................................................................71

1

1.0 Background

1.1 Introduction

On May 8, 1997, an explosion and fire occurred at the Bartlo Packaging

Incorporated (BPS) facility located in West Helena, Arkansas. As a result of the explosion and

fire three firefighters died and seventeen other firefighters required medical attention due to heat

exhaustion and minor injuries. Hundreds of residents, including local hospital patients, were

evacuated or sheltered in place due to the threat of exposure to toxic chemicals released in the

blast. Major roads were closed and the Mississippi river traffic halted. Several emergency

response groups participated in the response action. It took approximately two weeks to

extinguish the fire.

The Environmental Protection Agency (EPA) and the Occupational Safety and Health

Administration (OSHA) conducted a joint investigation of this event in accordance with a

Memorandum of Understanding (MOU) signed in November 1996. The agencies established a

joint chemical accident investigation team (JCAIT) made up of personnel from the EPA and

OSHA National Offices, OSHA=s Health Response Team, and Regional and contractor personnel

from both agencies. This report contains a description of the incident and the results of the joint

investigation.

1.2 Facility Description

BPS is a corporation with facilities in Helena and West Helena, Arkansas. The West

Helena facility is located in an industrial park three miles from the central business district of West

Helena, Arkansas. The facility is located in a flat area used primarily for agricultural purposes.

The nearest residential area is located less than one mile northeast, and the Mississippi river is

located approximately three miles east.

BPS is an agricultural chemical packaging facility. No chemical manufacturing occurs at

the facility. BPS receives bulk shipments of agricultural chemicals (pesticides, insecticides, etc.)

and repackages them in smaller, water soluble, containers. The operation is conducted for

chemical manufacturers using tolling contracts. Under a tolling arrangement a company contracts

with another company to perform a specific operation. In this case, chemical manufacturers

deliver agricultural chemicals in bulk containers, which BPS repackages according to the

manufacturers= specifications. BPS then ships the product back to the specified location.

The West Helena facility employs approximately 130 workers. At the time of the incident

65 employees were on duty. The facility consists of two production buildings (referred as units

One and Two), two satellite buildings, and a Agel@ building. The production buildings are

constructed of corrugated metal with steel reinforcement. The Unit Two building (Figure 1),
2
3
4

in which the incident occurred, had a 100' x 150' main area, a 16' x 34' loading dock, and two 50'

x 60' satellite buildings connected to the main area by breezeways. In October 1995, a warehouse

 addition was added to the Unit Two building. It shared the southern wall of the original building

(referred to as the new warehouse addition north wall). The addition was approximately 7800

square feet. It was also constructed of corrugated metal with the exception of the outside eastern

wall. This particular area had two stories with an exterior (eastern) wall constructed of cinder

blocks.

Repackaging operations in the Unit Two building required the use of two reciprocating air

compressors. The compressors were located in the southern portion of the original building. The

compressors= discharge pipes went through the new warehouse addition=s north wall into a

common header pipe (Figure 2). This header pipe was fifteen feet long and 5'11" from the

concrete pad floor. It ran parallel to the north wall to meet an after-cooler outside the new

addition=s west wall. The output from the after-cooler was piped back along the same wall 3'7"

from the concrete floor carrying the cooled air back to the accumulator tanks under each

compressor (Figures 3 and 4). 

 Figure 3. After-cooler Figure 4. Compressor Discharge

 Pipe After the Incident

1.3 Chemicals in the New Warehouse Addition

 The inventory information used by emergency responders during the response action was

based mostly on BPS= management recollection. The Agency of Toxic Substances and Disease

Registry (ATSDR) developed a table during the response action based on employee interviews

(After Action Report, BPS Pesticide Fire, ERSAB, ATSDR, August 4, 1997). Several weeks

after the incident, BPS provided to JCAIT information regarding the type and quantities of the

chemicals stored in the Unit Two building the day of the incident. Based on the BPS inventory
5

information and witness statements, the JCAIT determined that the following chemicals were

present in the Unit Two new warehouse addition at the time of the incident: Maneb 75DF,

Azinphos methyl (AZM) 50W, Alliette Signature WDG, Topsin WSB, Sevin 80 WSP, and

Penncozeb 75DF. Material Safety Data Sheets (MSDSs) for Maneb 75DF, Azinphos methyl

(AZM) 50W, and Alliette Signature WDG are included in Appendix A.

2.0 Description of the Incident

2.1 Sequence of Events

December 1995- May 7, 1997

In December 1995, BPS provided MicroFlow Company (MFC) a quotation to repackage

bulk AZM 50W into 1 lb. water soluble bags. BPS was to provide warehousing for a two-week

supply of materials being repackaged and two weeks prior to and following repackaging. As part

of the contract arrangement, BPS requested MFC to do a presentation to BPS workers and

managers on safety and health issues related to worker exposure and handling of the AZM 50W. 

The request was based on AZM=s toxicity. The presentation was to be delivered prior to the

repackaging operation.

On January 29, 1996, BPS sent a letter to MFC expressing concern about the

reactivity/flammability of AZM 50W. Their concern originated through a conversation with a

representative of Bayer Agricultural Division. Bayer noted that it had experienced a number of

incidents involving thermal decomposition and/or fires involving Guthion (Bayer=s AZM

formulation). The letter stated that many of Bayer=s fires were initiated in ribbon blenders and

transfer screws similar to those used at BPS. BPS noted in its letter that the Material Safety Data

Sheet (MSDS) provided by MFC did not have information to support a similar situation. BPS

questioned why the MSDS provided by MFC did not contain information similar to Bayer=s

MSDS on Guthion for flammability and reactivity. MFC=s MSDS (of January1995) had a

Hazardous Materials Incident System (HMIS) flammability and reactivity rating of 0 compared to

Bayer=s National Fire Protection Association (NFPA) rating of 2. BPS requested MFC=s advice

since they Ahave little experience dealing with reactive materials and depend on our customers to

inform us of any problems inherent in their materials@ (letter from BPS to MFC January 29,

1996).

MFC and BPS personnel met on February 8, 1996, to discuss the suitability of the BPS

packaging equipment and the apparent inconsistency on the AZM 50W fire and reactivity hazards.

 As a result, BPS proposed to construct a water deluge system to accommodate a potential

smoldering of the product. The parties agreed on a system that would run water lines to the

repackaging hopper, with valves located by the packaging room=s door. In case of a Abad odor@

while running the equipment, the operator was supposed to flood the hopper with water.

At BPS=s request, MFC made a safety presentation on February 12, 1996 to BPS workers
6

and managers. The presentation included product background, toxicity, safe work practices, and

fire/reactivity issues. 

On February 13, 1996, MFC sent a follow-up memo by telefax to BPS. It states that 

A...AZM 50W will begin to smolder and smoke at approximately 170 degrees Fahrenheit. This

temperature is consistent with the 167 degrees listed on our MSDS.@ In the same memo, MFC

stated that they were in the process of locating a sample of Guthion 50W to test and that they

would update BPS with any new findings. At the time of the incident MFC had not given any

additional information to BPS.

The MSDS for AZM 50W provided by MFC to BPS did not reference any 1670 F (750 C)

temperature. MFC used a 90% pure AZM technical grade as the AZM 50W active ingredient. 

The technical grade supplier has a 1580 F ( 700 C) temperature in their MSDS Aconditions to

avoid@ section.

May 7, 1997: Tifton, Georgia, MicroFlow Warehouse

MFC had made arrangements to ship two truckloads of AZM 50W to BPS from Tifton,

Georgia on May 7, 1997 via Milan Express. Each truckload contained 26 bulk bags (supersacks)

with approximately1600 pounds of AZM each. These supersacks are constructed of woven

polypropylene coated fabric and have a 45 cubic foot capacity. The supersacks on both trucks

had AZM 50W from batches produced from 10/96 to 4/97.

Prior to his arrival to Tifton, the first truck driver picked up the truck in South Bend,

Indiana. Then, he picked up plastic lawn mower parts in Elgin, Illinois and delivered them to

Macon, Georgia. At 2:45 p.m., MFC personnel started loading AZM 50W onto the first truck. 

Upon completing the loading, truck driver one left the Tifton warehouse at 3:45 p.m.

At 5:00 p.m. MFC personnel started loading the second AZM 50W truck. Truck driver

two had not hauled pesticides before. At 6:30 p.m., the second truck loaded with AZM 50W left

Tifton, Georgia bound for BPS.

May 7 - 8, 1997: Road

Truck driver one pulled over and rested for two hours at Wyona, Missouri. He stated that

 the AZM 50W odor was making him feel sick. He transported AZM 50W a year earlier from the

MFC plant located in Macon, Georgia. He stated that the AZM 50W smell was similar to the

previous truck load. The smell had made him feel sick both times, but this particular time it

Areally got him.@

Truck driver two stopped for an eight-hour rest in route to BPS. He stated that he could

smell the cargo from outside the truck. The AZM 50W smelled bad to him but did not make him

feel sick.
7

May 8, 1997 : BPS, West Helena, Arkansas

Before the 10:00 a.m. work break

Truck driver one arrived at BPS, Unit One at 7:20 a.m. He was received by a BPS

employee who directed him to Unit Two. Once in Unit Two, truck driver one broke the truck

seal at 8:00 a.m. The truck was not unloaded immediately because the fork lift operators were

unloading Procure empty drums. The Procure truck was unloaded by 9:55 a.m.

From 10:00 a.m. break to lunch break (11:55 a.m.)

BPS fork lift drivers began unloading the first truck after the 10:00 a.m. break. They had

to move other material in the new warehouse addition (empty cardboard and drums) to make

space for the incoming AZM. According to BPS forklift drivers the cargo was located along the

new warehouse=s north wall on a two row/double stack arrangement. They also stated that AZM

pallets were spotted approximately six inches from the north wall.

While unloading, fork lift drivers and nearby employees noticed and made comments

about the strong odor. They reported that the AZM in the first truck smelled worse than the

AZM in the second truck and the AZM repackaged at BPS one year earlier.

A fork lift driver reported a spill in the new warehouse addition right after the 10:00 a.m.

break. Twenty to thirty pounds of Alliette Signature had leaked from the top pallet of a 

previously patched supersack which had reopened. The spill reportedly occurred next to the new

warehouse addition north wall, near some empty drums on the west side. The BPS waste monitor

began to clean the spill up around 11:30 a.m. He used a forklift to move the top pallet of Alliette

and took it to the stretch wrap area. He then took the waste to room seven for disposal.

The second AZM truck arrived at 11:30 a.m., when the first truck had only two pallets left

to unload. BPS employees finished unloading the first truck close to lunch time. The first truck

pulled away from the loading dock. Another truck, reportedly carrying cardboard, pulled in and

stayed at the loading dock for approximately ten minutes. In the meantime, forklift drivers started

stacking two rows of Aother@ product to the north wall of the new warehouse addition. After the

cardboard truck pulled out, the second truck pulled into the loading dock. Truck driver two

broke the truck seal but one of the fork lift operators told him that the unloading would begin

after the lunch break.

Lunch break (11:55 a.m.-12:25 p.m.)

All work activities, with the exception of the spill cleanup, stopped during the lunch break.

 The BPS waste monitor completed the Alliette Signature spill clean-up around 12:20 p.m. He

called the shift supervisor to check on the spill clean-up.
8

Truck driver one was dispatched to Grenada, Missouri and left the site before the

explosion.

After lunch break (12:45 p.m.)

The forklift supervisor returned from lunch, then went back to the slitting room to wrap a

pallet. He was the first person to see the smoke. He described it as Aa yellow powder puffing

through the hole@ around the compressor header pipes. He reported that the smoke (or powder)

was coming from the new warehouse addition through the hole and forming in the air, not

dropping to the floor. He also stated that the powder had the same smell as the AZM that had

been unloaded earlier. He did not see fire but called Afire@ on the radio at what he thought was

approximately 12:50p.m. He grabbed a fire extinguisher and went to rooms eight, nine, and ten

to get people out. He then looked back to the compressor area and saw a large cloud of what

appeared to be powder. He tried to go into the warehouse area but the powder was too dense. 

Another employee was in the warehouse with an extinguisher. Neither employee used his fire

extinguisher; they left the unused fire extinguishers in the warehouse and evacuated. In the

meantime, the shift foreman called ACode Red@ and the evacuation process continued. Most

employees reported seeing yellowish smoke. Others reported the smoke color to be lime green. 

All the employees reported seeing the smoke coming from the new warehouse addition area

where the AZM had just been placed or through the wall holes around the compressor pipes into

the slitting room. Employees also reported a rotten egg/skunk odor.

The production manager called 911. The West Helena Fire Department (WHFD) received

first notification at 1:02 p.m. According to the 911 call transcription, BPS reported a small

smoldering fire with no flames. The production manager stated: Ais where some product was set

next to a hot line off an air compressor. It=s starting a little bit of a smother, but no fire. But it=s a

lot of smoke.@ The caller also referred to a 1,500 pound supersack. A second notification, to the

Helena Fire Department, was received at 1:09 p.m.

Three maintenance employees went to Unit Two after the radio fire call. All of them

reported seeing smoke coming through the holes around the compressor header pipes. They

described it as light yellow close to the roof and thick grey/tan near the floor. One of the

employees turned the exhaust fans on. Reportedly, this employee thought that Aone of the

supersacks of MicroFlow=s was leaning against the pipes.@ The other employee went to the

electrical panels (the electrical panel was adjacent to the compressors room on the way to the

breeze way leading to satellite one) and turned the compressors off. 

During the evacuation of Unit Two, truck driver two observed yellow Astuff@ coming out

of the back of the building. One of the fork lift operators told him that there was fire close to

some pipes. Without having unloaded any product, he closed the doors to the truck and pulled

his rig away from the loading dock, taking it across the street.

The shift foreman took a roll call and one employee was missing. A fire truck arrived at
9

1:15 p.m., just after the first roll call. The firefighters stated they thought yellow product was

coming from the building. The WH Fire Chief arrived shortly after the fire truck. One of the

firefighters received an MSDS from a BPS employee. He checked the Department of

Transportation (DOT) Hazardous Materials Booklet and noted that one of the products on site

was water-reactive. The production manager discussed the products= reactivity with the WH Fire

Chief. He gave the Fire Chief a binder with the MSDS and a floor plan. The WHFD department

called volunteers, other emergency services, and the Helena Fire Department for backup. After

consulting with the WH Fire Chief, the maintenance manager closed the three roll-up doors to the

loading dock and satellites one and two.

 Several BPS employees went to satellite one to locate the missing employee. He was

located upstairs in the reclaim area and escorted out. A second roll call took place and all

employees were accounted for.

The WH Fire Chief and the maintenance supervisor discussed the smoke location. The

Fire Chief observed that the Asmoke@ looked more like powder or product and that it was seeping

instead of puffing. The maintenance supervisor unlocked and opened a side door on the east side

of the new warehouse addition for a firefighter, but the yellow smoke was too thick for the

firefighter to enter. 

 The firefighter reported back to the WH Fire Chief. The WH Fire Chief asked the

production manager to show him the building layout to check the location of the smoldering

supersack. The WH Fire Chief then asked about the danger of an explosion and the BPS

President said there was none.

The four firefighters walked back toward Unit One to get a lifeline. They returned to the

Unit Two building close to the room 9 exterior wall (east wall). A bell started to ring inside the

building, and the maintenance supervisor explained to the firefighters that the sprinkler system

alarm had just gone off. The maintenance supervisor then observed water coming from the

sprinkler alarm on the east exterior wall indicating that the sprinkler system had in fact been

activated. At 1:34 p.m. the alarm company received a fire notification. (The on-site activation of

the sprinkler system sends an electronic notification simultaneously to the alarm company.) The

maintenance supervisor asked the firefighters to wait for him to turn the power off before entering

the building because the equipment was still energized.

The maintenance supervisor went to the exterior office door by the north side of Unit One

to attempt to disconnect the power to the building. The disconnect power box was located in an

interior hallway between the office and the maintenance shop. He entered the office and

proceeded to the door leading to the hallway. Suspecting fire, he felt the door and found it hot to

the touch. He cracked the door and observed that the shop area was full of smoke. He

determined that he could not reach the disconnect box safely and retreated. He notified the WH

Fire Chief that he was unsuccessful in disconnecting the power to the building.
10

An electrical company=s service man had an appointment with a nearby facility. He saw

the police and firemen and went directly to BPS. He tried to get in the building by the office

door, but felt heat on the walls and decided to turn the power off from the main power cutouts

outside near the transformer. He observed yellowish dust or smoke coming out of the vents. The

main power cut consisted of three individual legs. The service man pulled the first leg. As he was

getting ready to pull the second leg, an explosion occurred. A firefighter reported seeing a

mushroom cloud at the east side of the building. Another firefighter reported hearing a wuff

sound Alike throwing gasoline on a fire,@ at the same time he saw a massive fireball coming from

the building. The explosion caused the cinder block wall to collapse. The four firefighters

standing east of room 9 were struck by the collapsing wall. Three of them were killed and the

remaining one was seriously injured.

At the time of the explosion, the WHFD received a call from the New Jersey Bartlo

Packaging chemist. The fireman reported that the chemist asked whether the sprinkler system had

activated and explained to the firefighter that two different types of chemicals were present at the

site. According to the firefighter, the chemist said the chemicals would explode if water was put

on them.

At 1:39 p.m. the alarm company was notified of the explosion.

2.2 Emergency Response Actions

BPS Emergency Preplanning

 BPS was an active member of the Local Emergency Planning Committee (LEPC). BPS

had a written AEmergency Response and Contingency Plan@ dated September 1995. They had

made arrangements with the WHFD for emergency support and had provided copies of their

written plan and MSDSs. BPS had also invited the fire department to tour their facility and to

participate in their emergency drills. A West Helena firefighter stated that fire department

personnel had toured the facility approximately one month before the incident.

According to BPS employees, the facility had several fire extinguishers but they were to

be used only on non-chemical fires. Employees were instructed not to fight chemical fires but to

immediately evacuate the building. The Unit Two building reportedly had a fire alarm system

which was backed up with radios and intercom. Safety meetings covered evacuation routes. A

floor plan showing the evacuation routes was posted on the wall.

Initial Response

Upon being called to the site, the West Helena Fire Chief called in all volunteers and off

duty personnel. He also called the Helena Fire Department, the emergency medical services, the

State Police, and the Phillips County Office of Emergency Services. This office notified the State

Office of Emergency Services, schools and radio stations in accordance with the County and
11

LEPC Plan.

At the time of the explosion, the Helena Fire department had just arrived. The priority

immediately after the explosion was to rescue the injured firefighters and control the fire. Both

fire departments retreated from the fire after rescuing the only survivor from the reconnaissance

team. Police and emergency medical services also arrived on scene. Several firefighters were

treated on-site because of minor injuries and heat exhaustion. The fire chiefs issued an initial

evacuation order downwind of the smoke plume, including the Helena Medical Center, and called

the West Memphis HazMat team.

At 3:00 p.m. the West Memphis HazMat team arrived at the site to support fire fighting

efforts. They provided the first air monitoring equipment. Due to the extreme toxicity of the

chemicals involved and changing wind conditions, the evacuation was extended to a three-mile

radius area. Most of the Helena Medical Center patients were taken to a community college and

others to a hospital in Clarksdale Mississippi. Residents of West Helena and nearby Helena were

sheltered in place. A twenty-mile section of the Mississippi river was closed to river traffic due to

the prevailing winds at the time of the incident,. 

Response Actions Under the Incident Command System

At 2:06 p.m. the National Response Center notified EPA Region 6 of the fire and

explosion at BPS Inc. The initial notification had no information regarding fatalities, injuries or

evacuations. At 5:00 p.m., EPA received a second notification indicating that the incident was

out of control and requesting federal assistance. EPA Region 6 dispatched two On-Scene

Coordinators (OSC) and activated the Regional Response Team (RRT). Other federal groups

joined EPA in the response action. DOD=s Pine Bluff Arsenal provided atropine and real time air

sampling equipment. The atropine was intended to be used as an antidote for AZM exposure of

responders and community members.

The RRT contacted several chemical companies for scientific and technical support.

Among other companies, Mobay Chemical, DuPont, Bayer, Rhone Poulenc, and Elf Atochem

sent representatives to the site to voluntarily assist in the response action. DuPont also deployed

its HazMat team to provide emergency response support.

Response organizations continued air monitoring to determine if the plume contained

dangerous levels of toxins. Based on wind conditions and monitoring results the evacuation was

downgraded to stand-by status. Local authorities allowed evacuees in the two-mile radius return

to their homes.

On May 9, 1997, the Incident Command System (ICS) was officially implemented.

Numerous Federal, State, and Local agencies and organizations provided support within the ICS,

including US EPA, US ARMY, Arkansas State Police, Office of Emergency Services, West
12

Helena/Helena/ West Memphis Fire Departments, OSHA, US Alcohol, Tobacco, and Fire Arms

(ATF), Center for Disease Control, ATSDR, NFPA, DuPont, BPS, and others.

The EPA On-Scene Coordinator directed the response through the ICS operations. As

more information regarding the quantity and nature of the chemicals involved in the fire became

available, the fire was allowed to burn with minimal active fire fighting efforts. This decision was

made based on the potential water reactivity of the burning chemicals and the concern that

incomplete combustion products could be more harmful than those generated by complete

combustion. 

By May 14, 1997, Maneb was the primary chemical still burning at the facility. Maneb is

air reactive and water reactive. After several unsuccessful efforts to extinguish the fire,

emergency responders decided to spread the Maneb into thin layers and then to fog it with water.

This strategy was chosen based on information provided by Rhone Poulenc on a similar incident

in Brazil. All fire zones were extinguished and the site was downgraded from emergency

response. After inspection on May 15, 1997, the Arkansas State Police released the site from

crime scene status.

The EPA OSC opened the site for the JCAIT to take samples and document the scene

before the clean up activities could begin. The JCAIT coordinated site documentation, sample

planning, and sample collection with all the on-scene investigative parties. Once the JCAIT

completed sample collection, the EPA OSC released the site for cleanup. The BPS contractor

began cleanup operations under EPA=s oversight on May 22, 1997.

2.3 Public Health and Environmental Issues

Several response organizations, including EPA, Arkansas Department of Health, 

Mississippi Department of Environmental Quality, and the BPS contractor performed air

monitoring. This information was used to determine whether the plume could present a threat to

public health or the environment. Chemical companies provided technical assistance on

decomposition products and monitoring devices.

The Arkansas Department of Health requested on-site assistance from ATSDR to address

the following public health issues: 1) acceptable exposure levels, 2) hospital reoccupation, 3)

decontamination of business and residences, and 4) consumption of exposed food products.

On-site use of atropine was limited to one firefighter who exhibited exposure symptoms.

Reportedly, this firefighter was not wearing respiratory protection. Approximately 400 people

reported symptoms consistent with short term exposure to pesticides. Thirteen of those cases

were referred for blood tests. These blood tests were reported as normal.

The Arkansas Department of Pollution Control and Ecology collected point of entry water
13

samples from the community water system wells. The impact was found to be minimal because

runoff from fire fighting efforts was contained on-site and no drinking water wells were in the

vicinity of the facility. 

ATSDR=s after action report concluded that no long-term public health effects were

expected from the fire and explosion at BPS. This conclusion was based on the toxicology of the

chemicals involved and the maximum contaminant levels detected in and around the businesses

and residences.

3.0 Investigation and Analysis

3.1 Investigation

Members of the JCAIT interviewed BPS personnel and other individuals potentially

having knowledge about the incident. The JCAIT also requested documents from the facility,

documented the scene, and collected samples. Once the initial field activities were completed, the

JCAIT identified two distinct problem areas: the existence of a combustible atmosphere in the

new warehouse addition and the resulting three firefighter fatalities.

The primary focus of the JCAIT investigation is on the events leading to the creation of

the combustible atmosphere. Therefore, most of the initial investigation activities were conducted

to support the root cause analysis of this particular problem. The JCAIT acknowledged that other

investigation groups, such as the NFPA and the U.S. Fire Administration (USFA), were

addressing the three fatalities. It is not the intention of this report to duplicate the work

performed by these groups. Instead, this report looks at general areas in the emergency response

system that could have contributed to the firefighters= fatalities. 

The JCAIT did not attempt to analyze the explosion dynamics. Given the presence of a

combustible atmosphere, any source of ignition had the potential to initiate the explosion. 

However, the most likely source of ignition was the arc(s) created in the facility equipment when

the electrical company service man began disconnecting the power to the facility. The JCAIT did

attempt to identify the explosion origination point and the source of the combustible material in

the air as relevant to the immediate cause. The investigation team used witness statements,

photo-documentation of the area, and laboratory analysis in this process. The process required

several iterations of analytical work. Some of the laboratory results are not discussed directly in

this report because they were either inconclusive (did not confirm or disprove a conjecture) or did

not include any detectable contaminants levels. Summary reports on laboratory analyses are

included in Appendix B.
14

3.2 Analysis

3. 2. A Overview of Explosion Scenarios

BPS did not have standard operating procedures (SOPs) for material storage and handling.

The general practice at the facility was to store materials in the warehouse as space was made

available. There were no established methods to ensure segregation of incompatible materials or

protection of stored materials from factors that could cause accidental releases, ignition or reaction

of ignitible or reactive materials. According to the BPS Unit Two forklift supervisor, he was not

instructed to tell forklift operators where to spot materials in the warehouse. The fork lift

operators were supposed to find an Aempty spot@ to locate incoming materials. There was no

attempt to determine the material=s hazard classification and/or incompatibilities.

BPS conducted a hazard review before agreeing to repackage any product. The written

procedure required going through a check list before beginning a repackaging operation. The

hazard review did not address chemical handling and storage. There was no systematic review of

factors that could potentially affect warehousing of hazardous chemicals. For example, in October

1995, BPS added the warehouse area to the Unit Two building. The compressors= discharge pipe

was modified to pass through the new warehouse addition=s north wall and take a 90-degree elbow

turn to meet the outside after-cooler. This modification resulted in a fifteen foot long discharge

header pipe running at a height of 6 feet inside the pesticide storage area. No assessment of the

potential risks associated with this change was performed.

The incident occurred in early May, which is a peak production month for BPS as the

agricultural industry begins to prepare and place orders for various products for their growing

season. The morning of the event, forklift operators had to move materials around in the new

warehouse to make room for off-loading Procure and AZM. During the investigation, through

interviews of forklift operators and supervisors, investigators attempted to identify where materials

were spotted in the warehouse. The different accounts regarding what was located in the storage

area and where it was located indicated that there was no system in place to manage the storage of

the various materials at the facility. This lack of an inventory management system, storage SOPs,

and a system to review potential hazards of changes in the facility could have led to a number of

warehouse incidents. 

All witnesses agree that the smoke originated near the warehouse addition=s north wall,

close to the compressor header pipe. Witnesses, including the fire fighters, also reported the

presence of Aproduct@ or Apowder@ in addition to smoke in this area. This suggest the presence of

a hybrid dust/vapor mixture. The JCAIT found no visible crater for the explosion, which is

consistent with a dust/vapor explosion. The explosion of an airborne flammable vapor or dust

could occur at any location where a flammable concentration has accumulated. This could be at

some distance from the source of the dust/vapor mixture. Presumably, the fan located on the

southwest side of the building could have drawn the hybrid mixture in that direction, affecting also

the direction of the blast. In any case, the explosion origination point is not necessarily the
15

location of the flammable material source. The source of the flammable material will be discussed

in the scenario analysis.

Based on an event and causal factor diagram, analytical results, and professional judgment,

the JCAIT identified the following scenarios in the development of the combustible atmosphere

that led to the explosion:

$ Chemical inside supersack decomposes when placed close to the compressor header pipe

$ Decomposition of AZM 50W begins before arriving at BPS

$ Incompatible chemicals react

$ Malfunctioning compressor overheats a supersack

The JCAIT concluded that a supersack placed close or against the compressor header pipe

was the most likely scenario. Several of the chemicals stored in the new warehouse addition at the

time of the incident can decompose thermally while in contact with a surface within the

temperature range of the compressor header. However, the JCAIT concluded that AZM 50W had

a greater probability to initiate the event. It should be noted that most incidents are the result of

multiple factors rather than a single cause. The JCAIT did not rule out the possibility that the

AZM 50W placed close to the compressor pipe was already decomposing before arriving at the

facility. Following an initial decomposition of the AZM 50W, the Maneb adjacent to it could have

also been involved in the subsequent explosion. The explosion cause scenarios are discussed

below.

Scenario 1: Chemical in Supersack Decomposes when Placed Close to the Compressor

Header Pipe

 Critical to the development of this scenario was the need to determine if a supersack was

actually placed against the pipe, which chemicals were most likely to have been placed in such

proximity, and whether the compressor pipe could reach temperatures high enough to cause the

chemical to decompose. 

Compressor Discharge Temperature

 At the time of the incident, BPS personnel stated that the surface temperature in the pipe

was approximately 1450 F (630 C). In order to confirm this statement and determine the potential

involvement of the compressor in the incident, the JCAIT conducted a series of activities. First,

the team inspected and documented the compressor system conditions after the event. 

Observations from this inspection were supplemented with interviews with BPS employees and

management and the compressor manufacturer.

Second, the JCAIT conducted a forensic analysis of the compressors and estimated the

anticipated temperatures in the discharge pipe=s system. The analysis is presented in a report

dated August 20, 1997 and referenced as DNV Project No. 232-8384, Insecticide Warehouse
16

Explosion Investigation. The summary report is included in Appendix B.

Finally, the JCAIT participated in a simulation conducted by MFC at Tifton Industrial

Controls in Tifton, Georgia on May 15, 1998. The simulation intended to measure a range of

temperatures in a compressor system re-constructed to simulate BPS operations at the time of the

event.

Of particular interest was the surface temperature of the common header pipe at the

approximate point were the supersacks could have been spotted. MFC, with the concurrence of

OSHA and EPA, developed a testing protocol to provide and connect two compressors to

simulate the BPS conditions. The compressors were connected under EPA and OSHA oversight.

 The JCAIT measured the piping surface temperature at several locations and under different

conditions (insulated vs non-insulated).

 A summary of the findings is presented below:

$ The piping configuration between the compressors and the after-cooler included

approximately twenty feet of discharge piping and two short radius turns.

$ Discussions held with the manufacturer of the two compressors used at BPS indicated that

there are a number of factors which can affect the compressor discharge temperature such

as ambient temperature and discharge pressure. However, under normal operating

conditions the maximum discharge air temperature of the compressors at the cylinder head

would be expected to be in the range of 3000 to 3500 F (1490 - 1770 C).

$ JCAIT estimated that the discharge temperature on a compressor system like the one used

at BPS would be approximately 3500 F (1770 C). The associated external pipe

temperature would be 2800 F (1380 C). If the pipe is engulfed by an insulating type

material, such as a supersack, the pipe would be expected to attain the same temperature

as the discharge air. See DNV Project No. 232-8384 in Appendix B.

$ During the MFC=s Tifton simulation, the team measured the non-insulated pipe

temperature at the distance where the supersack could have been in contact with the

header pipe. Once equilibrium was reached, the surface temperature at that point was

approximately 2550 F (1240 C). The group then wrapped a two foot section of the pipe

with a fibrous glass insulation to roughly simulate the effect of a supersack against the

pipe. The temperature increased from 2550 to 3010 F (1240 to 1490 C) in less than 30

minutes. The maximum insulated header temperature in the simulation was 3360 F (1690

C).

The JCAIT also reviewed technical literature, including the compressor operator=s manual,

to determine how the BPS compressor system compares with industry practices:
17

$ The Operator=s Manual for the Model 460 Compressor, Overheating Section, states that

the piping to the after-cooler location should be as short as possible, preferably no more

than three feet. For runs over three feet, the pipe size should be increased by one pipe size

for each eight foot run. 

$ The Compressed Air and Gas Handbook, published by the Compressed Air and Gas

Institute, states that the discharge piping, i.e., the piping between the compressor and the

after-cooler, the after-cooler separator, and the air receiver, should be as short and direct

as possible and should use Along-radius@ elbows where bends are necessary. 

$ The American Society of Mechanical Engineers (ASME B19.1 - 1995) Safety Standards

for Air Compressor Systems, Section 2.1.8. High Temperature states, AExternal surfaces

subject to temperatures in excess of 1750 F (800 C) which personnel may have contact,

shall be guarded or insulated.@

The JCAIT concluded that the common header pipe connected to the two-compressor

discharges was in fact substantially higher than the 1450 F (630 C) estimated by BPS employees

and management. From the above results, the JCAIT estimates that the discharge header in the

warehouse could have been in excess of 3000 F (1490 C).

Chemical Location

Shortly after the incident, BPS employees and management identified the

decomposing material as an AZM supersack placed against or close to the hot compressor

discharge pipe. The JCAIT confirmed that supersacks of materials were being spotted in close

proximity or against walls at BPS. After the incident, JCAIT observed supersacks spotted along

the wall in the Unit One warehouse. In this case, the supersacks were stacked two-high. The

edge of the bottom supersack was within inches of the wall. The top supersack was listing so that

it was in contact with the wall (Figure 5).

Figure 5. Supersack set-up at BPS Unit One
18

Several of the chemicals stored in the new warehouse addition at the time of the incident

had the potential to decompose thermally while in contact with the hot compressor pipe. The

JCAIT collected bulk samples of the combusted residue where the explosion occurred, attempting

to determine the exact location of each chemical pallet. The analysis of these samples was of

limited use due to the total destruction of the area and combustion of the sampled material (Figure

6). The collection and analysis of samples was supplemented with the analysis of other physical

evidence and witnesses= statements.

 

 Figure 6. Aerial Photo BPS Unit Two

Based on witness interviews, the JCAIT identified the approximate location of the

chemicals in the warehouse area (Figure 7). Even though witness accounts are somewhat

conflicting regarding the quantity and approximate location of the stored chemicals, most

statements agree that AZM supersacks had just been placed next to the compressor piping. 

Witnesses also agree that the yellow smoke or powder was coming from this location. Forklift

operators recollect placing Maneb pallets by the compressor pipe in an attempt to make room for

the incoming AZM. In addition to the witness statements the JCAIT:

$ Screened the bulk residue samples for various pesticides including AZM, Maneb, Topsin,

and Sevin. Only semi-quantitative values of AZM and Maneb were reported.

$ Secured and analyzed the remains of the new warehouse addition ventilation fans which

had visible yellow residue (Figure 8). AZM and its major decomposition products were

confirmed.

The JCAIT concluded that it was highly probable that pallets of both AZM and Maneb

were placed along the compressor pipe the day of the event.
19
20

Figure 8. Ventilation Fan with Yellow Residue

AZM and Maneb Thermal Decomposition

Both AZM and Maneb can decompose thermally if they are exposed to elevated

temperatures during a period of time.

Maneb is classified by the Department of Transportation (DOT) for transportation

purposes as an ASpontaneously Combustible Material@ unless it is stabilized. If it is stabilized,

Maneb is classified as a ADangerous When Wet Material.@ This classification includes materials

that evolve flammable gas when in contact with water. Maneb presumably falls in this category

because of formation of carbon disulfide. According to the MSDS, the Maneb at BPS was

stabilized.

Data related to AZM decomposition temperature is rather conflicting. MSDS do not

identify AZM as flammable and most literature provides a decomposition temperature of 3200 F 

(1600 C). 

The JCAIT requested representative samples from the manufacturers of AZM 50W and

Maneb 75DF to conduct several thermal stability tests including decomposition temperature and

color changes associated with temperature. The JCAIT also conducted Differential Scanning

Calorimetry (DSC) tests on other AZM formulations, including the 90% pure technical

formulation used as the active ingredient in AZM 50W. A summary of the tests findings and

literature search are presented below:
21

AZM 50W

$ AZM 50W showed visible color change to dark tan at 2170 F (1030 C). The sample

showed visible smoke at 3400 F (1710 C).

$ The DSC analysis showed the 90% AZM technical formulation decomposing exothermally

(1100 J/g) at approximately 3200 F (1600 C). Other formulations, including AZM 50W,

decomposed exothermically (600 J/g) at approximately 3380 F (1700 C). The smaller

amount of heat released by the 50% formulations compared to the 90% pure technical

grade is consistent with the addition of inert ingredients.

$ A basket test to determine safe storage temperatures for bulk AZM 50W showed

decomposition of the sample beginning between 1580-1760 F (700-800 C). The

decomposition temperature corresponds to an estimated safe storage temperature of 790 F

(260 C), using a 10% safety factor, based on volume and surface area specifications for

supersacks provided by MFC. It should be noted that the test does not predict a safe time

interval corresponding to this temperature.

$ MFC conducted a twelve month storage stability study in support of registration of its

product. The procedure included the use of two 2.5 pound samples. For this test the

product was stored at 680 F " 360 F (200 C " 20 C) for twelve months. 

$ The EPA Office of Pesticides= Product Properties Test Guidelines (OPPTS 830.6317) for

pesticide registration requires storage stability tests to be conducted under either of the

following conditions: A) At 68 0 or 770F(200 C or 250 C); B) Under warehouse conditions

which reflect the expected storage conditions of the commercial product; C) The test

parameters may be expanded to include accelerated conditions, such as elevated

temperatures (1040-1290 F) (or 400-540 C) or cold temperature (-200-00 C).

$ In a test to determine whether it would melt, decompose, or the vapor given off would

ignite, the AZM sample turned yellowish brown, then black, gave off yellow smoke, and

the vapors ignited. A second test confirmed these results.

A study conducted by G. Bertoni and Co-workers; Lazioni Commerciali in Ambienti

Refrigerata,, Annali di Chimica, 1985, states that Aaccidental overheating of an AZM mixture may

occur during the mixing process and since the active principle melts at low temperatures

(m.p.1620 -1650 F) (m.p. 720-740 C) and decomposition begins at a temperature of about 2120 F

(1000 C), gases and vapors are set free.@ The study concluded that: 

$ The product begins decomposition around 1000 C. As temperature increases an intense

exothermic reaction occurs between 3380 and 3560 F (1700 and 1800 C) with a loss of

volatile products of about 40% of the initial weight.
22

$ AZM is a thermally unstable material; a slow process of degradation of the compound

occurs below 1220 F (500 C).

$ The spontaneous degradation of AZM is noticeably accelerated by any increase of

temperature so that attention has to be paid to storage of this product and its commercial

forms.

$ It is recommended to keep AZM away from any heating. If the temperature rises above

1000 C decomposition is very fast and at 1700-1800 C the product decomposes almost

instantaneously.

MANEB 75DF

C The sample of Maneb 75DF showed a black spot beginning at 3200 F. Visible smoke was

observed at 3400 F (1710 C).

$ Under nitrogen atmosphere, Maneb 75DF did not release a significant amount of energy

when heated during the DSC. In the temperature range of 3380-4100 F (1700-2100 C) the

samples heated in nitrogen showed an exothermic reaction followed by an endothermic

reaction. The net result under these conditions was a slight absorption of heat with

decomposition occurring at approximately 3380 F (1700 C).

$ Zi-Ru Liu, et al. published a study in Thermochimica Acta 220 (1003) 229-235 entitled

Heat Changes Associated with the Thermal Decomposition of Maneb and Zineb. This

study focuses on the heat changes on thermal decomposition of Maneb and Zineb using

DSC. It acknowledges that both endothermic and exothermic processes are present in

their initial decomposition. The study concludes that the initial decomposition

temperature in air is greatly decreased compared with that in nitrogen. The study

indicates that the thermal decomposition of Maneb is accelerated and is an exothermic

process accelerated in air or oxygen gas.

$ The basket test results for Maneb 75DF showed an onset temperature between 2210-2390

F (1050

-1150 C). Using similar procedures as described for AZM, an estimated maximum

safe storage temperature of 1810 F (830 C) was calculated for a supersack of Maneb. The

test does not predict a safe time interval corresponding to this temperature.

C When tested for melting, decomposition, and evolution of ignitible vapor, Maneb 75DF

decomposed into a black material, white vapors evolved from the decomposing sample,

the vapors ignited into a yellow/orange flame, and the vapor flame self-sustained several

seconds after the removal of the ignition source. In a second test Maneb produced vapors

that ignited as a yellow flame; at full decomposition the sample produced white smoke. 

.

As mentioned before, both AZM 50W and Maneb 75DF could have been placed close or
23

against the compressor header pipe. The test on both substances indicate that decomposition

could have occurred at the temperature likely reached by the compressor exhaust pipe, but AZM

begins to decompose at a lower temperature than Maneb. Statements provided by most witnesses

of the incident describe a yellow smoke or gas which is consistent with what was observed during

experimental tests.

The JCAIT concluded that AZM 50W was the material responsible for the initial evolution

of the combustible atmosphere. If a supersack of AZM 50W was placed in contact with or in

close proximity to the hot compressor pipe, the heat could have initiated its thermal

decomposition. The decomposing material would propagate away from the pipe in the direction

of the center of the supersack. The contact of the decomposing material with the pipe in this

instance would not necessarily be prolonged. The decomposition would be accompanied by the

evolution of gas and smoke (the products of decomposition). 

AZM=s volatile decomposition products, as all organic compounds, evolve flammable

constituents upon decomposition. In particular, a literature reference (Combustion Products from

Pesticides and Other Chemical Substances Determine by Use of DIN 53 436, L. Smith-Hansen

and K. Haahr-Jorgensen, Fire Safety Journal 23(1994), 51-66), lists six organic combustion

products from the decomposition of AZM. The article further states that generally, large numbers

of different organic species are formed during decomposition due to incomplete decomposition

and partial oxidation. As mentioned before, the flammable gases from decomposition would not

have been confined to the immediate area above the supersacks and could have ignited/exploded

at some distance from the origination point.

Scenario 2. AZM decomposition begins before arriving to BPS:

The JCAIT postulated as a possible scenario that a thermal decomposition was occurring

inside a supersack of AZM 50W before it arrived at BPS. This decomposition could have

generated the airborne flammable substances that exploded in the warehouse. The scenario is

supported mostly by witness statements concerning the smell of the supersacks that were

unloaded the morning of the event. The truck driver reported that the AZM 50W smell had made

him feel sick and that he had to stop and rest for that reason. On separate interviews, BPS

employees stated that he had made the same remarks to them the morning of the incident. Other

BPS employees reported the unusual smell as well.

Chemical powders can undergo smoldering combustion. Hot temperature spots can

become entrapped in bulk containers (e.g. a supersack). Smoldering can also occur as a result of

self heating when the temperature of a bulk material is raised to a level at which the rate of heat

production exceeds the rate of heat loss. In either case, the container and contents can thermally

insulate, allowing exothermic reactions to continue at a very slow rate. When the container is

disturbed, the reaction can spread and the reaction rate can increase until the self heating reaction

reaches the surface. The hot material or its decomposition products may reach temperatures

sufficient to burst into flames, especially when disturbed.
24

Less= Loss Prevention in the Process Industry, volume 2; 17.5 explains as follows: AA dust

deposit can undergo smoldering for a long period. It is not unknown for large piles to smoulder

for a matter of years. Both air access and heat loss are restricted so that combustion is very slow,

but is sustained. Such smouldering may give no readily detectable effects. In particular, there

may be no smoke or smell from the burning. This delay between ignition and outbreak of flaming

can create hazards. Fire may break out unexpectedly in a factory shut down overnight or at a

weekend, or the cargo of a ship may be discovered to be on fire when it is unloaded. Hazards of

dust fires include those of a dust explosion resulting from the formation and ignition of a dust

suspension, of the ignition of other flammable materials and of the evolution of toxic combustion

products.@

The AZM unloaded at BPS the day of the incident was contained in supersacks

approximately1600 pounds of material each. The product had been stored in Tifton, Georgia. 

NOAA reported a daily average temperature of 760 F (240 C) for Tifton, GA during the month of

April. The maximum temperature reported by NOAA for Helena, Arkansas on May 8, 1997 was

820 F (280 C).

MFC files show eight minor incidents from 1987-1996. These incidents were associated

with AZM 50W smoldering as a result of the material coming in contact with hot surfaces (mostly

hot bearings) during production. In those instances, MFC flooded the smoldering product with

water. A manufacturer of another AZM formulation reported twelve incidents in the 1960's, five

in the 1970's, and seven in the 1980's. All of them involved excessive heating during processing

or storage. As stated in previous sections, MFC had discussed with BPS the product=s potential

for smoldering while in contact with hot bearings. Reportedly, MFC advised BPS to flood

production hoppers in the presence of a bad odor during the repackaging operation.

In theory, one of the AZM 50W supersacks could have had a smoldering hot spot as a

result of the mixing operations. A smoldering spot in a bulk container could have been in storage

without being detected. Sensors normally used in automatic fire protection systems cannot

usually detect this kind of condition. This hot spot could have initiated a self heating reaction

which accelerated during the unloading at BPS. The smoke or powder was discovered right after

the lunch break. There is an approximate 15 minute time span from the time the waste monitor

left the new warehouse addition, and the smoke was discovered. After the discovery, the reaction

seemed to have continued at an increasingly accelerated rate. An accelerated reaction rate after

being disturbed is consistent with industry=s experience of smoldering spots insulated by the bulk

container.

The scenario, however, is based solely on witness statements. These statements are not

consistent. Thermally stable AZM has a very strong and persistent odor. The truck driver and

BPS employees were not familiar with AZM. Their statements concerning whether or not this

load had a different odor from a previous one are at times contradictory. 
25

The JCAIT inspected the truck several days after the incident looking for evidence of

AZM 50W decomposition. Prior to the incident, the truck had transported plastic lawn mower

parts. Therefore, there was no potential for the AZM 50W to react with a compound previously

transported in the truck. Wipe samples conducted in the truck confirmed only the presence of

AZM. Early AZM decomposition products would be in the form of volatile gases and vapors. 

Since several days had passed since the incident, it was not reasonable to expect positive sampling

of volatile compounds.

The JCAIT requested MFC split control samples from the production batches offloaded at

BPS. Laboratory analysis showed no signs of thermal decomposition. The fact that the control

samples showed no signs of decomposition, however, does not rule out the possibility of a hot

spot entrapped in a supersack. In addition, these control samples have been in a controlled

environment that could be substantially different from actual storage conditions. Similarly, there

is no evidence that the AZM supersacks delivered at BPS were exposed to factors that could

induce its thermal decomposition.

The JCAIT concluded that this is a possible scenario but the available evidence is

uncertain and cannot substantiate it. However, the team acknowledges that a self heating process

could have either initiated the event or accelerated the thermal decomposition of a supersack

placed close to a heat source.

Scenario 3. Incompatible Chemicals React

 

The following pesticides were present in the Unit Two new warehouse addition at the time

of the incident: Azinphos methyl 50W, Maneb 75DF, Alliette Signature WDG, Topsin WSB,

Sevin 80 WSP, and Penncozeb 75DF. In addition, a spill of twenty to thirty pounds of Alliette

Signature was reported next to the new warehouse addition north wall shortly before the incident.

The team reviewed the chemical properties and reactivity of these pesticides to estimate

potential hazardous reactions that could have initiated the explosion and subsequent fire. This

review is discussed below and summarized in the table at the end of this section. The pesticides

present represent the following types of chemicals:

C Carbamate - Topsin and Sevin;

C Dithiocarbamate - Maneb and Penncozeb; and

C Organophosphorus - Azinphos methyl and Alliette.

The analysis showed that none of the pesticides would be expected to be highly reactive

with each other under normal conditions. Based on their chemical structures, there would be no

reason to expect any of these substances to react with each other if they were accidentally mixed

together. The form in which these substances were stored (i.e., solid formulations) and the

presence of inert ingredients would make reactions particularly unlikely.
26

The carbamates and Dithiocarbamate are chemically similar; chemical reactions would not

be expected to take place between such similar chemicals. Maneb and Penncozeb (Mancozeb), in

particular, are compounds of the same base chemical and are very similar; Maneb is the

manganese salt of dithiocarbamic acid, and Penncozeb is a compound of dithiocarbamic acid and

both manganese and zinc. Topsin (Thiphanate methyl), a carbamate, is combined in formulations

with both Maneb and Mancozeb (Farm Chemicals Handbook, 1994), indicating that o reaction

takes place when these substances are mixed. There appears to be no reason to expect a reaction

between the carbamates Topsin and Sevin (carbaryl), because of their chemical similarity, or

between Sevin (carbaryl) and Maneb or Penncozeb, by analogy with Topsin.

Alliette (Fosetyl-aluminum) and Azinphos methyl are Organophosphorus compounds, not

carbamates or Dithiocarbamate, but no reaction would be expected upon mixing with carbamates

or Dithiocarbamate, based on the chemical structures of these substances. Fosetyl-aluminum is

combined in formulations with Mancozeb (Farm Chemicals Handbook, 1994), indicating that no

reaction would take place between these substances. This type of formulation also provides

evidence that Fosetyl-aluminum likely would not react with Maneb, because Maneb is very similar

to Mancozeb, and would be expected to react similarly.

Several of the pesticides are reported to be incompatible with strong oxidizers, and it is

likely that all of them would react with strong oxidizers under some conditions. No oxidizers

were reported to be present, however. Based on this analysis, the JCAIT concluded that the

event was not initiated by the Alliette Signature spill or the reaction of incompatible chemicals

placed in proximity.
27

Reactivity and Flammability of Pesticides Present in New Warehouse Addition at BPS

Name Common Name/Chemical Name/Formula

of Active Ingredient

Reactivity and Flammability Data Potential Reactions with Other

Pesticides Present

Azinphos

methyl

Azinphos methyl

O,O-(Dimethyl S[(4-oxo-1,2,3-benzotriazin3(4H)-yl)methyl] phosphorodithioate

C10H12N3O3PS2

Decomposes at elevated temperatures.

Hydrolyzed in alkaline and acidic media. Contact with

strong oxidizers may cause fires and explosions.

Combustible (conflicting data).

None expected.

Topsin Thiophanate-methyl

Dimethyl[(1,2-phenylene)bis

(iminocarbonothionyl)]bis(carbamate)

C12H14N4O4S2

Compatible with other agricultural chemicals that are

neither highly alkaline nor contain copper.

No data on flammability (probably combustible).

None expected. May be combined in

formulations with Maneb and Mancozeb

(Penncozeb), indicating no reaction.

Alliette

Signature

Fosetyl-aluminum

Aluminum tris(O-ethyl phosphonate)

C6H18AlO9P3

Stable under storage conditions.

Incompatible with strong bases, mineral acids, strong

oxidizers, strong reducing agents.

Non-flammable.

None expected. May be combined in

formulations with Mancozeb (Penncozeb),

indicating no reaction.

Sevin Carbaryl

1-Naphthyl Bmethyl carbamate

C12 H11NO2

Stable under storage conditions.

Incompatible with alkalies and strong acids.

Combustible.

None expected.

Maneb Maneb

Manganese ethylenebis(dithiocarbamate)

(C4H6MnN2S4)x

Decomposes on prolonged exposure to air or water. 

Incompatible with strong acids and strong oxidizers.

Classified by DOT as spontaneously combustible or

dangerous when wet.

None expected. May be combined in

formulations with Thiphanate-methyl

(Topsin) and Mancozeb (Penncozeb),

indicating no reaction.

Penncozeb Mancozeb

Manganese ethylenebis(dithiocarbamate)

complex with zinc ion

(C4H6MnN2S4)x(Zn)y

Stable under storage conditions. 

Decomposed in acid and alkaline conditions, by heat, and

when exposed to moisture and air. Incompatible with

strong acids and strong oxidizers.

Compatible with most common pesticides.

No data on flammability - probably similar to Maneb.

May be combined in formulations with

Thiphanate-methyl (Topsin) and Maneb,

and with Fosetyl-aluminum (Alliette)

indicating no reaction.

Sources:

Farm Chemicals Handbook >94.Hazardous Substances Databank (HSDB), National Library of Medicine, for Azinphos methyl, Fosetyl-aluminum, Maneb, Mancozeb.

MSDS for Azinphos methyl 50W, Alliette Signature, Sevin, Maneb 75DF, Penncozeb 75DF.

TOMES for carbaryl. Worthing, ed., The Pesticides Manual (1987).]
28

Scenario 4. Malfunctioning Compressor Overheats Supersacks Near the After-cooler Piping

Two multistage reciprocating air compressors were used in the Unit Two building. As stated

previously, these compressors discharged into a common header pipe that was located on the

warehouse side of the wall, approximately five feet above the deck. This header was 15 feet long and

led to an after-cooler outside the building. The 15-hp unit suffered substantial damage during the

incident. After the explosion, this unit was found lying on its side with no lubricating oil in the

crankcase. The concrete foundation by the compressor had substantial heat damage and spalling in a

configuration that suggested a liquid had burned on the surface. The 20-hp unit had only moderate

damage, remained in its upright position after the event, and had a substantial amount of oil in the

crankcase.

The JCAIT dismantled the 20-hp compressor. The 20-hp compressor did not show any

observable internal damage. The JCAIT also performed a forensic analysis of the 15-hp unit to

determine whether or not the unit was working properly at the time of the event (DNV Project No.

232-8384). The forensic analysis conducted on the 15-hp compressor showed that:

C The aluminum bell housing for the electric motor and the aluminum header for the first stage had

melted away. The melted residue had been deposited on the engine and compressor mount

platform immediately below the motor when it was still in the upright position. This indicates

that the compressor was exposed to heat before falling on its side.

C The pulley side of the compressor had sustained direct flame impingement heat, but little was

observed on the opposite side. The damage areas indicate that an intense fire had been burning

on the deck next to the pulley side while the compressor was still upright.

C The connecting rod and journal bearings had not been scored. This indicates that the unit had

sufficient lubrication when last run.

C A coke-like residue was inside the crankcase. This indicates that a lubricating oil fire had

developed inside. Presumably, it was ignited by a liquid fire on the deck after the compressor

fell over. It is also likely that the oil leaked out through the pulley side bearing.

Based on these findings, JCAIT concluded that the 15-hp compressor was not malfunctioning

before the event. Therefore, this scenario was discarded by the investigation team.

3. 2. B Overview of Early Emergency Response

There are many factors that could be root causes or could have contributed to the three

firefighter fatalities. A formal analysis requires a thorough review of operational parameters and human

performance influencing factors including training, competency, pre-planning, policies and procedures,

etc. A critique of these factors and the local emergency response activities is outside the scope of this

investigation. However, the JCAIT evaluated some general aspects of the emergency response system

(related to the BPS explosion) which can foster unsafe situations. By doing this, the JCAIT attempts to

promote efforts to provide local emergency response groups with information critical to their safety

when responding to chemical incidents.
29

BPS personnel believed and informed the WHFD that a smoldering Abag@ of AZM had initiated

the incident. This fact is indicated in witness accounts, the BPS 911 call transcript, and an early press

release from the facility management. As a repackaging tolling operator, BPS did not have in-house

expertise to test and identify the hazards associated with the chemicals they were handling. Instead,

BPS was relying on the chemical manufacturer=s information (in this case MFC) to address the chemical

hazards. On the other hand, the WHFD relied on BPS to provide them with chemical hazard

information. 

On-site information

BPS management told the WH Fire Chief that AZM would not explode. Neither the facility

personnel nor the documents handed to the fire department conveyed the danger of explosion. The

MSDS for AZM used by the BPS personnel and firefighters was provided to BPS by MFC. The

MSDS includes the following information concerning the thermal stability and reactivity and

flammability hazards of AZM 50W:

$ HMIS flammability rating of 0 (non-combustible).

$ HMIS reactivity rating of 0.

$ Stable under normal conditions.

$ High temperatures may cause hazardous vapors.

$ Store in cool, dry, well ventilated place. Do not place near heat or open flame.

There is no data on the AZM 50W indicating the possibility of an explosion hazard. It does not

include a safe storage temperature or a decomposition temperature. It does, however, warn against

placing AZM near heat. The JCAIT reviewed several other MSDS for different AZM formulations, in

particular, the MSDS for Bayer=s Guthion, which BPS had discussed with MFC. This MSDS includes

the following information:

$ NFPA flammability rating of 2. (JCAIT Note: An NFPA flammability rating of 2 applies to

materials that must be moderately heated or exposed to relatively high ambient conditions before

ignition can occur. These materials would not under normal conditions form hazardous

atmospheres with air, but under high ambient temperatures or under moderate heating might

release vapor in sufficient quantities to produce hazardous atmospheres with air.)

$ NFPA reactivity rating of 2. (JCAIT Note: An NFPA reactivity rating of 2 applies to materials

that are normally unstable and readily undergo violent chemical change, but are not capable of

detonation. It applies to materials that can undergo chemical change with rapid release of

energy at normal temperatures and pressures and materials that can undergo violent chemical

changes at elevated temperatures and pressures.)

$ During routine handling of this material, there should be little risk of dust explosion.
30

$ Stable material. Unstable in sustained temperature above 100 oF (380 C).

$ Storage temperature: 30-day average not to exceed 100 oF.

$ Store in cool, dry area away from heat source.

It should be noted that NFPA 472 Standard on Professional Competency of Responders to

Hazardous Material Incidents, 1997 edition, Non mandatory Appendix A-21.4 explains that: ASome

materials have products of combustion or decomposition that present a significant greater degree of

hazard that the inherent physical and toxic properties of the original material. The degree of hazard is

dependent on the conditions at the time of the incident@.

In addition to the AZM 50W, the WHFD had the DOT=s Emergency Response Guidebook. In

the 1993 edition, Guide Number 55 applies to AZM. In the Fire and Explosion Section, Guide 55

indicates A Some of these materials may burn, but none of them ignites readily. Container may explode

violently in heat of fire.@

The WH Fire Chief reported during an interview that fire personnel received the following

HazMat training; two career firemen (both killed during the event) had 80 hours of technician level

training; all fire personnel had training through the awareness level; and other firemen were trained

through the technical and operational level. As part of the emergency preparedness program, the

WHFD received MSDSs from BPS and had been invited to tour the facility and participate in their

emergency response drills. As mentioned before, the fire department had toured the facility one month

before the incident.

 Training and pre-planning are critical to emergency response groups. Additionally, adequate 

information is essential for incident-specific risk management. Chemical emergency situations are

among the worst work environments for human performance. It is in emergency situations where the

human information processing system is burdened with multiple and critical tasks. The information

provided to local emergency responders has to be structured and prioritized for this specific use to

maximize human performance.

MSDSs are developed to comply with OSHA=s Hazard Communication Standard to 

communicate the hazards posed by chemicals to employees. Additionally, they are extensively used by

emergency response groups during chemical releases. The JCAIT looked at the MSDSs present at BPS

at the time of the incident from a local emergency response standpoint. The number of MSDSs at BPS

do not constitute a statistical representation of the MSDSs developed by the chemical industry. 

Evaluating the MSDSs present at BPS, the JCAIT found the following:

. 

$ MSDSs did not have a standard format. Information relevant or critical during an emergency

response operation may not be readily available or may be presented in a confusing format.
31

$ Some MSDSs had a check-box format. In the case of the Maneb MSDS, information was

incomplete or conflicting. For example, hazard information stated the chemical was Awater

reactive.@ However, the information on firefighting stated Ause water.@ No further explanation

on how the firefighting water will interact with the Maneb was provided (e.g. should the

firefighters use fog vs a large stream). Similarly, no information was provided related to Maneb

being stored in the presence of a water-based sprinkler system. 

$ Some terms were not clearly explained. In the case of the AZM 50W MSDS, information

included in the section AUnusual Fire and Explosion Hazards@ stated that the Avapors and fumes

from fire are hazardous.@ The term hazardous does not convey whether the vapors and fumes

are toxic, combustible or both.

The JCAIT concluded that the on-site hazard information was conflicting and incomplete. It is

critical that fire departments collect as much hazard information as possible within the time, resources,

and training limitations. In addition to MSDS, NFPA 472 Standard on Professional Competency of

Responders to Hazardous Material Incidents, 1997 edition, Appendix A Explanatory Material,

identifies other sources of information for hazard identification such as the North American Emergency

Response Guidebook, hazardous material databases, technical information centers

(CHEMTREC/CANUTEC/SETIQ), shipper/manufacturer contacts, and monitoring equipment.

Risk Perception/Risk Management

The WHFD was reviewing MSDSs when the explosion occurred. The firemen that died were

close to the building getting ready to enter the building. From witness interviews they were trying to

locate the smoldering Abag@ in the warehouse.

BPS employees were not aware of any explosion hazards. The employees did not show extreme

concerns to the WHFD. The facility personnel conveyed more the need of air-packs due to the toxicity

of the chemicals rather than any fire and explosion hazards. The production manager had entered the

building several times just before the explosion. He actually closed the building doors (with the fire

chief approval) which in effect confined the combustible atmosphere.

The lack of awareness of the potential explosion hazard played an important role in the tactics

used by the WHFD. With a better understanding of the potential hazards, the WHFD would

presumably have been more cautious. NFPA 1561, Standard on Fire Department Incident Command

System, Explanatory Appendix A-4-1.2, explains that the risk to fire department personnel is the most

important factor to be considered by the incident commander in determining the strategy to be

employed in each situation. One of the factors involved in the management of risks levels is the

pessimistic evaluation of changing conditions.

NFPA 1561, 4-1.2 states that AThe concept of risk management shall be utilized on the basis of

the following principles: (a) Activities that represent a significant risk to the safety of personnel shall be

limited to situations where there is a potential to save endangered lives; (b) Activities that are routinely

employed to protect property shall be recognized as inherent risks to the safety of personnel, and

actions shall be taken to avoid these risks; (c) No risk to the safety of personnel shall be acceptable

where there is no possibility to save lives or property@.
32

NFPA 1561, A-4-1.3, further explains: AThe acceptable level of risk is directly related to the

potential to save lives, the risk to fire department personnel must be evaluated in proportion to the

ability to save lives, the risk to fire department personnel must be evaluated in proportion to the ability

to save property of value. Where there is no ability to save lives or property, there is no justification to

expose fire personnel to any avoidable risk, and defensive fire suppression operations are the

appropriate strategy.@

As stated in the previous section, the on-site information available to the WHFD was conflicting.

 The AZM 50W MSDS did not state the potential for an explosion hazard. In addition, BPS

management may have given the WHFD a false sense of risk when asked about the danger of an

explosion. However, chemical warehouses may present unique and unexpected hazards to emergency

responders because of unknown combustion products and chemical interactions. In the BPS incident,

the building had been evacuated and no lives were threatened. Factoring conflicting information and the

unexpected hazards presented in a chemical storing area into the risk management decision process

could have helped the emergency responders to develop a safer response strategy. 

4.0 Root Causes and Recommendations

4.1 Root Causes and Contributing Factors

Root causes are the underlying prime reasons, such as failure of particular management systems,

that allow the faulty design, inadequate training, or deficiencies in maintenance to exist. These, in turn,

lead to unsafe acts or conditions which can result in an accident. Contributing factors are reasons that,

by themselves, do not lead to the conditions that ultimately caused the event; however, these factors

facilitate the occurrence of the event or increase its severity. Although the JCAIT cannot precisely

determine the exact cause of this event, there is sufficient information to support several root and

contributing causes. The root causes and contributing factors of this event have broad application to a

variety of situations and should be considered lessons for industries that conduct similar operations. 

The JCAIT identified the following root causes and contributing factors of the event:

$ MFC and BPS did not have a full understanding of the hazards associated with AZM.

EPA=s Office of Pesticides requires manufacturers to conduct storage stability tests under one of

the following conditions: A) At 200 C or 250 C; B) Under warehouse conditions which reflect the

expected storage conditions of the commercial product; C) The test parameters may be expanded to

include accelerated conditions , such as elevated temperatures (or 400 C-540 C) or cold temperature (-

200 C-00 C). MFC conducted the study at 200C " 20 C for twelve months and a two pound bag. In

order to comply with the Office of Pesticides requirements, MFC should have tested for the actual

container size (1,600 pounds) and expected storage and transportation temperatures which can be

considerably higher than the 200C used by MFC in their test.

 In addition, the Office of Pesticide Programs requires the use of DSC to test pesticides for

explosiveness. DSC is a screening test. For thermally unstable materials, the DSC test does not provide

specific enough information to predict safe storage temperatures of large storage or shipping containers.
33

MFC failed to provide BPS with adequate information on the hazards associated with the

chemical. As MFC did not perform adequate testing, hazard information relative to the thermal stability

and explosiveness of AZM was not included in the MSDS. 

$ BPS did not assess the potential hazards of a hot pipe in an area where hazardous

chemicals were to be stored when the new warehouse addition was constructed.

In October of 1995 BPS added the warehouse area to the Unit Two building. The compressors=

discharge pipe was modified to go through the area where hazardous chemicals were stored. A review

of the impact of the change should have identified the risks associated with this configuration to

workers and/or heat sensitive chemicals.

$ BPS did not have standard operating procedures for material storage and handling

Standard operating procedures could have prevented BPS from placing a thermally unstable

substance next to a heat source, in this case, the compressor header pipe.

$ On-site information provided to the WHFD was conflicting and incomplete.

The AZM 50W MSDS did not specifically identify an explosion hazard. Generally, chemical

hazard information on MSDS is not structured and prioritized for local emergency response use. 

MSDSs may not have enough information to help emergency responders conduct safe operations and

should not be relied upon as the sole source of information during an emergency response. In fact,

DOT=s Emergency Response Guidebook on-site had a warning related to containers exploding violently

in the heat of fire. Additional sources of information can help local responders to conduct safer

operations.

4.2 Recommendations

The following recommendations were developed by the JCAIT that address the root causes and

contributing factors to prevent recurrence or similar incidents at other facilities:

$ Manufacturers should be proactive in testing potentially hazardous materials. Testing for actual

conditions and elevated temperatures during storage should be conducted to determine safe

storage conditions. Screening tests, such as DSC, can be helpful in determining the need for

additional testing. However, thermally unstable materials which are intended to be packed and

shipped in large volume containers should be tested beyond screening levels.

$ Facilities which store, use, handle, manufacture, or move hazardous materials should develop

and implement a system to review potential hazards of modifications to facilities, equipment,

chemicals, technology, or procedures. The system should analyze potential impacts to safety,

health, and the environment and take appropriate actions before the modifications are

implemented. OSHA=s Process Safety Management (PSM), EPA=s Risk Management Program

(RMP), and the Center for Chemical Process Safety (CCPS) guidelines can help facilities

develop such system.
34

$ Facilities that store hazardous chemicals should develop standard operating procedures for

material storage and handling that address storage restrictions. Such facilities should adhere to

applicable practices outlined by CCPS and NFPA. Pesticide facilities are encouraged to also

follow NFPA 43D (Code for the Storage of Pesticides), specifically the non-mandatory

Appendix B.

$ Facilities storing hazardous chemicals should develop an inventory management system with

information regarding composition, compatibility, storage, location, and quantity of incoming

products. This management system can help the facility comply with storage restrictions and

provide emergency responders useful information during a response action.

$ EPA and OSHA, in conjunction with interested parties, should facilitate a workshop to make

recommendations on how to improve the quality of hazardous materials information available

during response actions. The workshop should review appropriate uses of MSDS by local

emergency response groups and how to provide these groups information describing the

behavior of hazardous materials when they begin to react or decompose and what responders

should look for during a chemical emergency.
35

Appendix A

AZM 50W, Maneb 75DF and Alliette Signature MSDSs
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51

16. OTHER INFORMATION 

National Fire Protection Association Hazard Ratings--NFPA(R):

2 Health Hazard Rating--Moderate 

0 Flammability Rating--Minimal

1 Instability Rating--Slight 

National Paint & Coating Hazardous Materials Identification 

2 Health Hazard Rating--Moderate 

0 Flammability Rating--Minimal 

1 Reactivity Rating--Slight 

Reason for Revisions: 

Conversion to ANSI MSDS format. 

Key Legend Information: 

ACGIH - American Conference of Governmental Industrial Hygienists 

OSHA - Occupational Safety and Health Administration 

TLV - Threshold Limit Value 

 PEL - Permissable Exposure Limit 

TWA - Time Weighted Average 

STEL - Short Term Exposure Limit 

NTP - National Toxicology Program 

IARC - International Agency for Research on Cancer 

ND - Not determined 

RPI - Rhone-Poulenc Established Exposure Limits 

Disclaimer: 

The information herein is given in good faith but no warranty, expressed or implied, is made. 
52

Appendix B

Summary of Laboratory Results
53

U.S. DEPARTMENT OF LABOR

OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION

SALT LAKE TECHNICAL CENTER

PHYSICAL MEASUREMENT AND ANALYSIS BRANCH

1781 SOUTH 300 WEST 

SALT LAKE CITY, UTAH 84165-0200

(801)-487-0073 ext. 272

FAX (801)-487-1190

12 December 1997

Report of analysis of samples for BPS, INC.

For smoldering point analysis, a volume of approximately 2mL of material was introduced into a

modified Setaflash© flashpoint tester. The tester was modified by having removed the cup cover so that

the test could be carried out as an “open cup” procedure. The material was heated up from room

temperature until smoking was observed and then until a visible change occurred to the material.

Sample J56676 (Azinphos) showed a color change to dark tan at 217(F. A further change to a dark redbrown color occurred as the temperature was increased. The sample showed visible smoke at

approximately 340(F.

Sample R68650 (Maneb) showed a small black spot beginning at about 320(F. The sample changed to

black increasingly as the temperature increased. Visible smoke was observed at 415(F.

The smoldering temperature results reported are given for sample test results performed under laboratory

conditions, and may not be representative of smoldering temperature value(s) resulting under differing

conditions.

Report of analysis of Samples V30707, V30708, V30709 from inspection of explosion at BPS, Inc.

Three samples were submitted for materials analysis on 6/4/97. They were assigned sample numbers as

shown below:

V30707 - Fiberglass exhaust north (hanging from the compressor line)

V30708 - Fiberglass Enclosure (burned remnant of fiberglass paneling).

V30709 - New, unused “Supersack”

V30707 showed continuous fiber fiberglass of diameter approximately 12 micrometers embedded in

white, brittle ash, consistent with a partially burned structural fiberglass panel. It was unclear as to

whether there was any latent supersack material left. The majority (80%) of the material remaining was

continuous fiber fiberglass

V30708 was continuous fiber fiberglass. The diameter of this fiberglass was nominally the same as for

V30707 at 12 micrometers. However, the index of refraction was different reflecting a different source
54

for the fiberglass by the manufacturer. Little other material was present other than a small amount of

powder adherent to the fibers.

V30709 appeared to be a way, fibrous synthetic material and was confirmed to be polypropylene by a

telephone call to Dorothy Hullett, an employee of Rexam Mulox, the bag manufacturer. Ashing of the

sack material at 500(C produced a black residue in an aluminum pan. No such residue was noted on

V30707.
55

U. S. DEPARTMENT OF LABOR

OCCUPATIONAL SAFETY & HEALTH ADMINISTRATION

Salt Lake Technical Center

1781 South 300 West

P.O. Box 65200

Salt Lake City, UT 84165-0200

801-487-0680

FAX 487-1190

Memo

DATE: November 4, 1997

MEMORANDUM FOR: Al Heins

THRU: Lois Moncrief, Jerry Schultz, and Mike Shulsky

FROM: Wayne Potter, David Armitage, Richard Lawrence, Pat Hearty,

and Joanna Shulsky

SUBJECT: Organic Division Analytical Results for BPS, Inc. and

 Microflow, Inspection # 6-009401

Analytical Screening

Samples J56742 through J56752 and J56755 through J56760 (field numbers 521-01

through 04, 521-06 through 11, Oil 1, 522-Fan SW, 522-Fan SE and 522-01 through 04)

were screened by HPLC for various pesticides including: azinphos-methyl, maneb, topsin

(thiophanate-methyl) and carbaryl (Sevin). Only azinphos-methyl and maneb were

reported, and their values should be considered as semi-quantitative only. Gas

Chromotagraphy-Mass Spectroscopy (GCMS) on J56742 (field number 521-01) confirmed

the presence of azinphos-methyl as well as some of its decomposition products, the major

one being O,O,S-trimethyl ester of phosphorodithioic acid. However, GCMS is unable to

determine if the decomposition products were present before analysis or created during

the sample analysis. J56742, as well as J56744, J56745 and J56758 (field numbers 521-

01, 521-03, 521-04 and 522-02 respectively) were also run by GC-FPD. Both

azinphos-methyl and the major decomposition product mentioned above were observed.

The samples reported as <QL for azinphos-methyl should be considered as maximum

values, the actual value would be less than the percentage reported. The values reported

for maneb on samples J56747 and J56760 (field numbers 521-07 and 522-04) are

minimum values, the actual value is greater than the reported value. Note: these samples

were not analyzed for fosetyl-aluminum (Aliette Signature).
56

1) Mass Spectroscopy

Azinphos-methyl was identified in sample J56755 (field number 522-Fan SW) by HPLC.

Azinphos-methyl could not be confirmed by GCMS, but the major decomposition

product, O,O,S-trimethyl ester of phosphorodithioic acid, was identified. However,

azinphos-methyl was confirmed in sample J56755 by GC-FPD. The material analyzed

was primarily the yellow stuff off of the fan. The other fan (sample J56756, field

number 522-Fan SE) had very little material on it, and was only screened for pesticides

(not including maneb).

2) Atomic Absorption

An initial screening for soluble aluminum compounds was performed by atomic

absorption analysis on samples J56700 through J56721 (bulk field numbers 1A, 2A,

2B, 3A, 3B, 4A, 4B, 5A, 5B, 6A, A1, AR, and also wipe field numbers BPS-1 through

BPS-10). The compound, fosetyl-aluminum (Aliette Signature) is a soluble aluminum.

Preliminary tests with a standard indicated that this procedure could be used to detect

the presence of fosetyl-aluminum. Unfortunately the samples all contained high

background levels of soluble aluminum and the results of this procedure was

inconclusive. Fosetyl-aluminum is used as a premix with mancozeb.

3) HPLC

A) Bulks

These same bulk samples (bulk field numbers 1A, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B,

and 6A) were given new lab numbers (J56637-46) and analyzed by HPLC-UV for

azinphos-methyl (0300), maneb (M177), thiophanate-methyl (D347) and carbaryl

(sevin, 0525). No detectable amounts of these compounds were found in any of

these bulk samples except 2B and 4B. Maneb was found on 2B and 4B.

B) Wipes

Similarly, the wipe samples mentioned in the paragraph above (wipe field numbers

BPS-1 through BPS-10) were also given new lab numbers (J56649-58 ) and

analyzed by HPLC-UV for azinphos-methyl (0300). Detectable amounts of

azinphos-methyl were found on samples J56649, J56650 and J56652 (field

numbers BPS-2, BPS-3 and BPS-1 respectively). These samples were each

confirmed by peak wavelength ratioing. 

C) Air Samples

J57349-53 (Field numbers A-1, A-2, A-4, B-1 and BLANK) were air samples that

were analyzed by HPLC-UV for azinphos-methyl and also a qualitative HPLC

analysis. No detectable amounts of analytes were found on these air samples.

4) Fosetyl-Aluminum Samples
57

These samples (bulk field numbers 1A, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6A, A1, AR,

and also wipe field numbers BPS-1 through BPS-10) have not yet been analyzed for

fosety-aluminum. Fosetyl-Aluminum is not compatible with the HPLC or ion

chromagraphy (IC) analysis. A method in the literature analyzed fosetyl-aluminum by

GC-FPD using a process of methylation. Several attempts were made to methylate

fosetyl-aluminum but our attempts were unsuccessful. So currently our laboratory does

not have a method for the analysis of fosetyl-aluminum. 

5) HPLC and GC

A) Repirator Mask Samples

A respirator used in the BPS Exposion was examined for contamination of the

organophosphorus insecticide Azinphos Methyl 50W, the fungicide Maneb and their

decomposition products. The respirator used during the evacuation by John

Fernirola was analyzed for any decomposition products. It was reported that John

Fernirola went into the smoke in effort to extinguish the source of the smoke. This

respirator worn by John Fernirola (E62546) appeared to be coated with smoke and

looked like a likely candidate to find the decomposition products. When Maneb is

heated, the major decomposition products are carbon disulfide and ethylene

thiourea. Carbon disulfide is collected with charcoal and ethylene thiourea is

collected with a glass fiber filter. The respirator used by John Fernirola was a 3M5300 using a 501 organic vapor cartridge. The cartridge has a glass fiber filter on

the outside and charcoal on the inside. The glass fiber filter was analyzed for

ethylene thiourea and the charcoal was analyzed for carbon disulfide. A portion of

the charcoal was desorbed with toluene and analyzed by gas chromatography

using a flame photometric detector. Carbon disulfide was not detected. A portion

of the glass fiber filter was extracted with water and analyzed by HPLC using a UV

detector. Ethylene thiourea was not detected. The outside of the mask was wiped

with several glass fiber filters soaked with methanol, toluene and water. These

wipes were analyzed by GCMS for analyte identification. GCMS identified 2-

naphthalenol, phthalate ester, and approximately C14-C18 acids. 

A portion of the glass fiber filter covering the charcoal on the organic vapor cartridge

was extracted with acetonitrile and analyzed by HPLC using a UV detector.

Azinphos-methyl was not detected on the glass fiber filter or the charcoal portion of

the cartridge. Mass spectroscopy also analyzed samples from the cartridge of the

mask. GCMS identified limonene, ethanol, isopropanol, methyl chloroform,

ethalfluralin, aliphatic C9-C10 (approximately), terpene, C3-C4 benzenes,

dichlorobenzene, and siloxane on the charcoal from the cartridge. GCMS identified

naphthalenol, dursban, O,S-dimethyltetrachlorothioterephthalate, an ethyl ester of

a long chain acid, phthalate esters, and a couple of unidentified compounds,

including an unknown amine, on the glass fiber filter portion of the cartridge.
58

Results

Air Samples

Azinphos-methyl Qualitative HPLC for other Compounds

J57349 ND ND

J57350 ND ND

J57351 ND ND

J57352 ND ND

J57353 BLANK BLANK

Bulk Samples

Field# Azinphos-methyl Maneb Topsin Carbaryl

J56637 1A ND ND ND ND

J56638 2A ND ND ND ND

J56639 2B ND .03% ND ND

J56640 3A ND ND ND ND

J56641 3B ND ND ND ND

J56642 4A ND ND ND ND

J56643 4B ND .6% ND ND

J56644 5A ND ND ND ND

J56645 5B ND ND ND ND

J56646 6A ND ND ND ND

Field # Azinphos-methyl Maneb

J56742 521-01 9.0% 4.0%

J56743 521-02 .06% .06%

J56744 521-03 .3% .08%

J56745 521-04 .2% .08%

J56746 521-06 ND ND

J56747 521-07 .003% 2.0%

J56748 521-08 .002% ND

J56749 521-09 .01% .1%

J56750 521-10 ND ND

J56751 521-11 .004% ND

J56752 OIL 1 NA NA

J56753 FGLAS EXN NA NA

J56754 FGLAS END NA NA
59

J56755 522-FAN SW 1.3% ND

J56756 522-FAN SE ND NA

J56757 522-01 .006% .06%

J56758 522-02 .02% .001%

J56759 522-03 .01% .03%

J56760 522-04 .02% 5.0%

Field # Aluminum (as Al), Soluble Salts

J56700 1A 5.0%

J56701 2A 9.0%

J56702 2B 8.0%

J56703 3A 7.0%

J56704 3B 6.0%

J56705 4A 9.0%

J56706 4B 9.0%

J56707 5A 6.0%

J56708 5B 8.0%

J56709 6A 9.0%

J56710 A1 .2%

J56711 AR .8%

Wipes

Field # Azinphos-Methyl

J56649 BPS-2 46.0 )g

J56650 BPS-3 43.0 )g

J56651 BPS-7 <QL

J56652 BPS-1 110.0 )g

J56653 BPS-5 ND

J56654 BPS-6 ND

J56655 BPS-4 ND

J56656 BPS-8 <QL

J56657 BPS-9 ND 

J56658 BPS-41 BLANK

Field # Aluminum (as Al), Soluble Salts

J56712 BPS-2 NA

J56713 BPS-3 NA

J56714 BPS-7 NA

J56715 BPS-1 NA

J56716 BPS-5 NA

J56717 BPS-6 NA

J56718 BPS-4 NA

J56719 BPS-8 NA

J56720 BPS-9 NA

J56721 BPS-10 BLANK
60

Respirators

Field # CS2 Ethylene Thiourea Azinphos-methyl Maneb

E62546 EPA001 ND ND ND NA

HPLC and GC analysis by Dave Armitage and Wayne Potter

AA analysis by Richard Lawrence

GC-Mass Spec. analysis by Pat Hearty and Joanna Shulsky

Compiled and written by Wayne Potter
61
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63
64
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67

Differential Scanning Calorimetry Results 

Root Cause Investigation of Explosion at Bartlo Packaging South, Inc. 

NEIC Project SPOO30 

INTRODUCTION 

On May 8, 1997, an explosion took place at the Bartlo Packaging South, Inc. facility in West Helena,

Arkansas. NEIC is assisting the joint EPA and OSHA investigation by providing information obtained by

differential scanning calorimetry (DSC) on the decomposition of two pesticides. The DSC results give

the amount of energy released by decomposition and the temperature at which decomposition occurs. 

BACKGROUND 

The two pesticides analyzed by NF-IC are Azinphos-methyl (AZM) and Maneb. Eight samples of

AZM were received from the OSHA lab. Two samples of AZM were sent directly to NEIC by the

Agriculture Division of Bayer Corporation in Kansas City, Missouri. These are labeled Guthion, which is

Bayer's name for A.ZM. One is Guthion Technical, which is 93.6% AZM, and the other is Guthion 50%

Wettable Powder (WP), which is 50% AZM. The Guthion Technical is from Batch No. 7030105, and the

Guthion WP is from Batch No. 7030063, according to the information supplied by Bayer. A sample of

Maneb 75DF was received from the OSHA laboratory in Salt Lake City. It was packaged in 23 separate

bottles for shippino, purposes. Three of the bottles were analyzed by DSC. 

When a material undergoes a chemical change such as a decomposition, heat is either absorbed or

released. Often decompositions are initiated simply by raising the temperature of the materials.

Differential scanning calorimetry is a method for measuring the heat released or absorbed during a

decomposition or other reaction. The differential scanning calorimeter gradually increases the

temperature of a reference cell and a sample cell. If a reaction of the material in the sample cell takes

place which either releases or absorbs heat, the DSC measures the amount of heat involved and the

temperature at which the reaction starts, called the onset 

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Uncertainty in determining the baseline contributed to imprecision in the heat release data. The 

DSC data for AZM and Maneb were not as reproducible or accurate as the data for the standard, which is

the melting of metallic indium. There are several reasons why this occurs. Organic substances do not conduct

heat as well as metals. Decompositions which produce gaseous or volatile products, such as those of AZM

and Maneb, show more variation. 

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Appendix C

References
73

References

ATSDR, ERSAB, After Action Report, BPS Pesticide Fire, August 4, 1997.

American Institute of Chemical Engineers, Center for Chemical Process Safety; Guidelines for

Preventing Human Error in Process Safety, ISBN 0-8169-0461-8, 1994

American Institute of Chemical Engineers, Center for Chemical Process Safety; Guidelines for Safe

Storage and Handling of Reactive Materials, ISBN 0-8169-0629-9, 1995

American Institute of Chemical Engineers, Center for Chemical Process Safety; Guidelines for Safe

Warehousing of Chemicals, ISBN 0-8169-0659-9, 1998

Bertoni and Co-workers, Annali di Chimica 76; Lazioni Commerciali in Ambienti Refrigerati, 1985

Det Norske Veritas (USA) Inc, Memorandum Report; Insecticide Warehouse Explosion Investigation,

DNV Project No. 232-8384, August 20, 1997

EPA Office of Prevention, Pesticides, and Toxic Substances; Product Properties Test Guidelines OPPTS

830.1000, 830.6316, 830.6317, August 1996.

Fire Safety Journal 23,1994; Smith-Hansen and K. Haahr-Jorgensen; Combustion Products from

Pesticides and Other Chemical Substances Determine by Use of DIN 53 436

Less, Frank; Loss Prevention in the Process Industry, Second Edition, Butterworth-Heinemann, 1996 

Mississippi Department of Environmental Quality; A final Engineering Report for Ambient Air quality

Monitoring for the BPS Inc Fire,, Jackson, Mississippi, May 1997

NFPA 43D; Code for the Storage of Pesticides, 1994 

NFPA 231; Standard for General Storage, 1995

NFPA 472; Standard on Professional Competency of Responders to Hazardous Material Incidents, 1997 

NFPA 1561; Standard on Fire Department Incident Command System, 1995

Zi-Ru Liu et al, Thermochimica Acta 220 (1003) 229-235; Heat Changes Associated with the Thermal

Decomposition of Maneb and Zineb.